Drainage systems for receiving fluid flow are well known in the art. Such systems provide a path for fluid flow from surface areas and often transport the fluid from surface areas directly to the ocean, rivers, lakes, estuaries, streams and the like without regard to the removal of debris, pollutants or other contaminants. For example, because of the Federal Environmental Protection Agency's Clean Water Act, controlling pollution from storm water runoff is receiving ever-increasing attention at all levels of government, Federal, State and local. Federal and state agencies have issued mandates and developed guidelines regarding the prevention of non-point source (storm water caused) pollution that require local governments to act upon or initiate.
Because of the aforementioned mandates, many cities and special districts have developed plans and taken action to prevent storm water pollution. These actions range from those that are educational in nature (labeling storm water inlets with phrases such as “No dumping—Flows into Rivers and Streams”) to active measures to remove pollutants. Such measures generally require the installation of equipment for removing contaminants somewhere between where the storm water enters the drainage system and the ultimate body of water receiving the runoff.
Several types of equipment are employed to reduce pollution and contaminants from storm water runoff. Catch basin filtration systems use devices installed at the point that the storm water enters the drainage system. The water flow is directed through an installed adsorbent material that aids in removing contaminants from the storm water while allowing the water to flow into the drainage system. Such a permanently installed catch basin filtration system is disclosed in U.S. Pat. No. 5,720,574. In addition to catch basin filtration systems, oil/water separators are employed. Such systems generally comprise large underground holding tanks that allow silt and pollutants to settle to the bottom of the tank and the water to flow into the drainage system. Other systems also exist to remove contaminants from water runoff. However, these systems are also generally permanent installations that are expensive to install and maintain.
As various maintainable catch basin filtration systems for filtering storm water runoff have been developed additional problems have evolved. An initial problem involves the installation of these systems in the wide variety of drain inlets and catch basins that currently exist. Drain inlets and catch basins have wide variances in dimensions, particularly in overall volume and distance across the mouth of the opening. Accordingly, fixed-dimension filtration systems are thus unable to account for variances in catch basin dimensions. Accordingly, catch basin filtration systems having varying dimensions are desired.
Moreover, because such filtration systems typically require regular maintenance, issues arise such as ease of access and the length of time that a system can operate between cleaning or replacing filter elements or other parts. Access to elements that must be cleaned or replaced is problematic in some systems, such that a heightened burden is placed on those who regularly maintain these systems. In addition, silt, sediment and other debris tend to settle on or around filter elements in many filtration systems, such that the length of time that these elements can effectively filter storm water runoff is significantly reduced. Therefore, catch basin filtration systems having improved accessibility for maintained parts and longer periods of effectively filtering storm water runoff before requiring maintenance are desired.
Another significant problem that has emerged in the development of catch basin filtration systems is the ability of such systems to process large quantities of fluid during peak flow periods without having backups or stoppages that result in localized flooding of surrounding areas. Peak flow periods would include, for example, extreme storm conditions or other flood type conditions. Due to concerns over storm drainage backups that can result in localized flooding, many filtration systems employ some form of a high-flow bypass feature that allows excess fluids to proceed through the drainage system without being filtered during periods of high fluid flow. As a result, these types of filtration systems have an upper limit for the amount of fluid that can be filtered at any given time as well as a maximum capacity for the amount of fluid that can be passed through the system in any event.
In practice, many catch basin filtration systems have proven to be inferior in one or both of these areas, with the result being that the filtering of storm water runoff is inadequate and/or that these systems become backed up and flood the surrounding local area. As some filtration systems have attempted to overcome these problems by increasing the volume of the fluid retaining trough or reservoir in the filtration system, these systems have encountered problems in maintaining the shape of the reservoir during periods of high flow. In these filtration systems, the reservoir tends to expand under the increased weight of the contained fluid, such that the expanded reservoir can fill the entire inner catch basin and partially or wholly block the high flow bypass and other fluid routes. This then results in a backed up drainage system and localized flooding. Accordingly, catch basin filtration systems having increased flow capacity for both filtered flows and high flow bypass flows are desired. In addition, it is desired that the fluid retaining reservoir in such systems substantially retain its overall shape during periods of high flow such that unwanted blockages and flooding are avoided.
In addition, the high flow bypass in many current filtration systems is effectively unable to restrain large objects or “floatables,” such as cigarette butts, during high flow periods. These objects typically pass through the filtration and drainage systems unimpeded whenever the high flow bypass is utilized in these systems. Accordingly, catch basin filtration systems that inhibit or restrain large objects or floatables from passing through high flow bypass areas are desired.
An added concern involves the need for filtration systems that are adapted for unusual or oddly shaped drainage channels or systems. One example of such a drainage system is the type of “trench drains” that are frequently employed at entrances to or within gas stations, industrial yards, parking lots and the like. These trench drains are notable in that they are fairly long and narrow, and tend to be of a shallow depth underneath a slotted cover grate place over the top. A typical trench drain will measure from six to twelve inches in width and from four to twelve inches in depth, although dimensions can vary. The length of a trench drain varies widely depending on specific site dimensions, but most range from six to twelve feet in length. Trench drains may occasionally be shorter than six feet, however, and some have been known to have lengths as long as 150 feet or more. When greater lengths are desired for a particular location, it is standard practice to align essentially several trench drains end to end, rather than to create one unduly long cover grate to cover a lengthy trench drain. Due to these relatively narrow and shallow dimensions, there is very little space within a trench drain, such that accommodation of a standard catch basin filtration system is not possible. Accordingly, filtration systems adapted to the narrowed dimensions of a trench drain are also desired.
Chitosan is a well-known material that is derived from a naturally occurring substance called chitin, which is a polysaccharide found in the exoskeleton of shellfish such as shrimp, lobster, and/or crabs. While chitosan has recently gained popularity as a dietary supplement, its inherent ability to generate small electrical charges has also provided benefits in the processing of contaminated items, such as wastewater. In turbid or polluted water, the electrical charges given off by chitosan react with the small electrical charges in pollution, fine silt and sediment particles, such that many of these tiny bits of contamination and silt coagulate together into larger chunks. These larger coagulated chunks of particles can then be filtered more easily from the fluid and are also more prone to settle to the bottom of the fluid body via gravity. An appropriate application of chitosan can render muddy water as fairly clear in a short period of time. While chitosan and chitin have been previously used to some extent in the treatment of wastewater, their use has yet to reach the field of storm water runoff with its accompanying objective to filter or clarify such water. Accordingly, more effective devices and systems for filtering or clarifying fluid passing through such devices and systems are also desired.